Read the published paper here (open access): [https://doi.org/10.1371/journal.pone.0171931][1] Read a summary of this research on the PLOS blogs: [http://blogs.plos.org/yoursay/2017/02/14/researcher-first-person-why-context-matters-when-assessing-autistic-traits/][2] **Abstract** Many of the personality and behavioral traits (e.g., social imperviousness, directness in conversation, lack of imagination, affinity for solitude, difficulty displaying emotions) that are known to be sensitive to context (with whom?) and reference group (according to whom?) also appear in questionnaire-based assessments of autistic traits. Therefore, two experiments investigated the effects of specifying contexts and reference groups when assessing autistic traits in autistic and non-autistic participants. Experiment 1 (124 autistic and 124 non-autistic participants) demonstrated that context matters when assessing autistic traits (*F*(1,244) = 267.5, *p* < .001, η2p = .523). When the context of the Broad Autism Phenotype Questionnaire was specified as the participants’ out-group (e.g., “I like being around non-autistic people” or “I like being around autistic people”), both autistic and non-autistic participants self-reported having more autistic traits; when the context was specified as the participants’ in-group, participants reported having fewer autistic traits. Experiment 2 (82 autistic and 82 non-autistic participants) demonstrated that reference group matters when assessing autistic traits (*F*(2,160) = 94.38, *p* < .001, η2p = .541). When the reference group on the Social Responsiveness Scale was specified as the participants’ out-group (e.g., “According to non-autistic people, I have unusual eye contact”), autistic participants reported having more autistic traits; when the reference group was their in-group, autistic participants reported having fewer autistic traits. Non-autistic participants appeared insensitive to reference group on the Social Responsiveness Scale. Exploratory analyses suggested that when neither the context nor the reference group is specified (for assessing autistic traits on the Autism-Spectrum Quotient), both autistic and non-autistic participants use the majority (“non-autistic people”) as the implied context and reference group. **File Directory** - Excel Data File: [https://osf.io/c2jhe/][3] - Text Data Files: available in OSF Storage under the Data Files component [1]: https://doi.org/10.1371/journal.pone.0171931 [2]: http://blogs.plos.org/yoursay/2017/02/14/researcher-first-person-why-context-matters-when-assessing-autistic-traits/ [3]: https://osf.io/c2jhe/